Solar power plants, e.g., solar photovoltaic (PV) power plants, which also can be referred to as fields, solar fields, or power plants, can occupy relatively large tracts of land and can include tens or even hundreds of thousands of solar panels. Some maintenance or diagnostic tasks can be done from time to time throughout the entire power plant. These tasks can include one or more maintenance tasks such as cleaning the solar panels, clearing snow off the panels, trimming vegetation between rows, depositing herbicide, insecticide, or animal repellant, solar panel inspection, structural inspection, identifying individual solar panels by bar code, spraying protective coatings on electrical connection points on the backs of panels, depositing coatings on solar panels, applying a material on the ground to increase reflectivity, or other suitable task(s).